Hermetic motor-compressor unit



M... @JQ

1960 J. NICHOLAS ET AL 2,948,458

I HERMETIC MOTOR-COMPRESSOR UNIT Filed Dec. 3, 1958 ANDREW J. NICHOLAS HENRI SOUMERAI INVENTORS BY N M 2,948,458 HERMETIC MOTOR-CONIPRESSOR UNIT Filed Dec. 3, 1958, Ser. No. 777,919 4 Claims. (Cl. 230- 58) This invention relates to improvements for a hermetic motor-compressor unit in which the motor and compressor are housed in separate compartments and are mounted on opposite ends of a common shaft extending through a partition forming the said separate compartments for the motor and compressor.

From the viewpoint of structural stability, the preferred location for a bearing supporting the shaft in this type of unit is in this partition. Yet if so located in presently known hermetic units, the lubricant supplied to the bearing from the lubricant sump in the compressor or crankcase compartment would only pass through the said hearing running clearance and into the motor compartment thereby increasing already existing lubricant handling problems. .More particularly, since gas leaks from the compression cylinders in the crankcase compartment and increases the pressure of this compartment beyond that of the motor compartment, difiiculty is encounteredv returning the lubricant from the motor compartment back to the lubricant sump in the crankcase compartment.

Apart from the location of the bearing, difliculty, in handling lubricant is also encountered due to the use of refrigerants miscible with lubricant, and the usual practice of cooling the motor with the suction gas of the refrigeration system which results in the precipitation of lubricant from the said gas within the motor compartment.

Accordingly, it is an object of the present invention to alleviate these problems'in the handling of lubricant in hermetic motor-compressor units. a

More particularly, it is an object-to alleviate these problems with certain improvements in construction to the extent that the hermetic unit of the present invention has its shaft supporting bearing in the preferred location in the said partition forming the separate compartments, but without adverse consequences. i

Not only do the improvements of the present invention permit locating the bearing in the partition, but they are also useful in operatively mounting a vacuum producing means on the shaft to prevent lubricant separating from the refrigerant gas from accumulating in the motor compartment, as for example in the manner taught in US. Patent 2,673,026 issued March 23, 1954, the said vacuum producing means in the present invention, however, being operatively mounted on the shaft in an improved manner due to these said improvements.

In the improved hermetic motor-compressor unit of the present invention the shaft supporting bearing is located in the partition forming the separate compartments for the motor and the compressor, and an element is rotatably mounted on the shaft adjacent the bearing and forms therewith a first :and a second annular chamber. The first annular chamber seals off the bearing running clearance and is provided with passage means to the crankcase compartment through which lubricant from the bearing passes directly to the crankcase compartment aided by gravity and by the pumping action of the shaft rotating within the bearing. The second annular chamber communicates with ejectors carried by the said rotatable nited States Patent element, and further is provided with passage means to the motor compartment through which gas is exhausted from the motor compartment. Accordingly, the pressure of the crankcase is reduced below that of the motor compartment and under these favorable pressure conditions, lubricant in the motor compartment flows through a check valve in the partition back to the lubricant sump in the crankcase compartment.

The invention will be better understood when considered in connection with the accompanying specification and single drawing forming a part thereof, in which drawing is shown a longitudinal View, partly in section, of the improved hermetic motor-compressor unit of the present invention.

Referring to the drawing, the hermetic motor-compressor unit 1 of the present invention is shown to be housed in an integrated casing, generally designated 2, in which there is a partition 3 dividing the casing interior into a compressor or crankcase compartment 4 and a motor compartment 5. Carried centrally of the partition 3, as for example by a weld thereto, is a conventional type journal bearing 6. A single shaft 7 for the unit extends through the bearing 6 and is connected at the end within the crankcase compartment 4 to a crankshaft 8, and at the other end within the motor compartment 5 to a rotor 9 of a motor 10. On the cranks 1 1 of the crankshaft 3 there are the usual connecting rods 12 connected to reciprocate pistons (not shown) within compressor cylinders 14. v

The refrigeration system with which the unit 1 is operatively associated is not shown since it does not form an ber 30 effectively seals essential part of the present invention. However, it will be understood that in operation, refrigerant gas and lubricant returning from the system is first admitted through an inlet connection 15 into the motor compartment 5, to be drawn through the motor 10 to cool this unit. After cooling the motor "10, the gas passes through an opening 16 into the compressor suction manifold 17, and from thence is admitted through suitable inlet connections (not shown) into the compressor cylinders '14. This results in the deposit of lubricant in the motor compartment 5 which for efficient operation of the unit must be returned through a check valve 18 on the crankcase side of the partition 3 to the lubricant sump 19 in the crankcase compartment 4. From sump 19, the lubricant is pumped by pump 20 through drilled passageways 21 in the crankshaft 8 and cranks 11, and thus is distributed to the bearing surfaces of the connecting rods '12 and also into the bearing running clearance space 22 of the main bearing 6. Also for eflicient operation of the unit, the portion of this lubricant which flows through the bearing running of clearing space '22 towards the motor compartment 5 must be prevented from spilling into this said compartment.

To alleviate these lubricant handling problems, the shaft supporting bearing 6 is provided with a cylindrical projection 23 extending laterally into the motor compart-ment 5, and this projection is counterbored forming an inner bore 24 and an outer bore 25. Securely mounted on the shaft 7 adjacent the bearing 6 between the shaft shoulder 26 and the rotor 9 so as to rotate with the shaft 7, is an element 27 having two annular shoulders 28 and 29 which extend into the said bores 24 and 25.

More particularly, the shoulder 28 extends part-way into inner bore 24 forming a first annular chamber 30, and shoulder 29 likewise extends part-way into outer bore 25 forming a second annular chamber 31. Conventional sealing 0 rings 32 in the locations shown are provided to make the said chambers 30 and 31 leakproof.

It will thus be appreciated that first annular chamolf bearing running clearance space 22 on the end nearest motor compartment 5 and thus prevents spillage of lubricant into the motor compartment 5. Even more important, an inclined passageway 33 is provided in the lower portion of the bearing 6 connecting the firstannular chamber 30 directly to the crankcase compartment 4, and through this passageway lubricant entering the first annular chamber 30 readily returns to the crankcase compartment 4 aided by gravity and by the pumping action of the shaft 7 rotating in the running clearance space 22 of the bearing 6.

In addition, element 27 readily lends itself to the solution of the difiicult lubricant handling problem occasioned by the precipitation of lubricant from the refrigerant gas being admitted into the motor compartment 5 to cool the motor 10. To this end, a passageway 34 is provided through the upper portion of bearing 6, so as not to weaken the shaft 7, and connects the crankcase compartment 4 to the second annular chamber 31. Through this passageway refrigerant gas is drawn from the crankcase compartment 4 by a vacuum created by a plurality of ejectors 35 carried by element 27 rotating with shaft '7. These ejectors 35 are simply hollow tubes inserted in suitable openings in the element 27 and communicating at their inner ends with second annular chamber 31 through passageways '36. In withdrawing gas from the crankcase compartment 4, the pressure of this compartment is reduced below that of the motor compartment 5, and thus check valve 18 will open permitting lubricant to pass from the motor compartment 5 to the sump 19 in crankcase compartment 4.

Thus, the hermetic motor compressor unit 1 of the present invention has greater structural stability due to the location of the bearing 6 in the partition 3, and this is accomplished without increasing lubricant handling problems. Further, the manner as hereinabove described by which this is accomplished, also permits use of a vacuum producing device for controlling lubricant flow between the compartments in an improved manner.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown, but that they may be widely modified Within the invention defined by the claims.

What is claimed is:

1. In a hermetic motor-compressor unit in which the motor has a rotor and the compressor has pistons, the combination of a crankcase compartment, a motor compartment through which suction gas passes to the compressor, a partition separating the compartments, a bearing in the partition, a shaft extending through the bearing and connected at one end to the rotor of the motor and at the other end to the pistons of the compressor, a passageway through said bearing and providing communication between the crankcase compartment and motor compartment, an ejector mounted adjacent said bearing and including a suction inlet communicating with said passageway for flowing gas from the crankcase compartment to the motor compartment, and a check valve in the partition for returning lubricant from the motor compartment to the crankcase compartment.

2. In a hermetic motor-compressor unit in which the motor has a rotor and the compressor has pistons, the combination of a crankcase compartment, a motor compartment through which suction gas passes to the compressor, a partition separating the compartments, a bearing in the partition, a shaft extending through the bearing and connected at one end to the rotor of the motor and at the other end to the pistons of the compressor, an element mounted on said shaft and abutting said bearing and including a chamber therein, a passageway in said bearing and communicating the crankcase compartment with said chamber, an ejector mounted on said element and having a suction inlet connected to said chamber to flow gases from the crankcase compartment to the motor compartment, and a check valve in the partition for returning lubricant from the motor compartment to the crankcase compartment.

3. in a hermetic motor-compressor unit in which the motor has a rotor and the compressor has pistons, the combination of a crankcase compartment, a motor compartment through which suction gas passes to the compressor, a partition separating the compartments, a hearing in the partition, -a shaft extending through the bearing and connected at one end to the rotor of the motor and at the other end to the pistons of the compressor, said shaft and said bearing spaced from each other to provide a running clearance therebetween, an element including a first and second chamber mounted on said shaft and abutting said bearing whereby said first chamber communicates with said clearance between the bearing and the shaft, means communicating the first chamher with the crankcase compartment, a passageway in said bearing and communicating the crankcase compartment with said second chamber, an ejector mounted on said element and having a suction inlet connected to said second chamber to flow gases from the crankcase compartment to the motor compartment, and a check valve in the partition for returning lubricant from the motor compartment to the crankcase compartment.

4. The hermetic motor-compressor claimed in claim 3 wherein the means communicating the first chamber with the crankcase compartment comprises an inclined passageway in said bearing and opening at one end into said first chamber and at the other end into the crankcase compartment.

2,673,026 Gerteis Mar. 23, 1954 

